Many of the existing hand-propelled wheelchairs designed for improved power efficiency do not account for certain repetitive motion injuries that are particularly problematic for the wheelchair-bound population. While power may be the focus of these devices, the potential damage to even the most hearty of those who use such devices is catastrophic to the mobility of the wheelchair-bound, should injuries even as innocuous as tendonitis. Such injuries are often overlooked in wheelchair design, because they are not so devastating to the mobility of an able-bodied person.
Furthermore, wheelchairs designed for high-speed use, may not account for the day-to-day needs of the wheelchair-bound individual either with regard to comfort, ease of use, or maneuverability in small spaces such as restrooms, common carriers, and commercial offices. Thus, generally the more rugged or powerful the wheelchair, the less appropriate it is for convenient everyday use. Other vehicles, such as U.S. Pat. No. 6,352,274 (which is incorporated by reference for all purposes) to Brian Redman may be designed for certain-aspects of human-powered mechanical efficiency, but do not address the needs of the disabled, such as use in a confined space, and are therefore not appropriate for adaptation for use in a wheelchair.
A regular wheelchair with only “hand rim” propulsion provides no mechanical advantage (MA) and are therefore it is hard work to propel long distances, and especially difficult up hill. It is also has the disadvantage that power is interrupted and energy is wasted every time the hand rim is gripped and released because the mechanism is not continuous. For many wheelchair users, to propel over long distances can be strenuous and stressful on the shoulders and wrists. Hand cycles are limited mainly to outdoor use because they lack maneuverability.